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Uz korak rapidnom razvijanju nanoindustrije u posljednjih nekoliko desetaka godi- na, trend mijenjanja perspektive na mikroskopsku razinu javlja se i u području medi- cine. Od njihovog otkrića u drugoj polovici prošlog stoljeća, nanočestice su pokazale izniman potencijal u poboljšanju metoda liječenja ljudskih bolesti. Javlja se varijetet nanočestica poput micela, biokompatibilnih polimera, mikročipova i sličnih, no pose- ban naglasak stavlja se na liposomalne nanočestice. Liposomi su sferične strukture veličine 50–450 nm sastavljene od jedne ili više koncentričnih fosfolipidnih membrana koje su organizirane tako da ”glave” fosfolipida vanjskog sloja i ”glave” fosfolipida unu- tarnjeg sloja dvosloja graniče s vodenim medijem. Upravo zbog ovakve orijentacije fosfolipida, liposomi imaju mogućost inkapsuliranja lipofilnih (unutar samog dvosloja)i hidrofilnih (unutar središnjeg vodenog medija) tvari. Metode pripreme liposoma nisu striktno ograničene pa je tako moguće prilagoditi osnovni model prireme prema želje- nom ishodu, a to je dobivanje liposoma specifičnog dizajna koji će inkapsulirane tvari dostaviti do specifičnog tkiva. Dizajn liposoma može se razlikovati s obzirom na njiho- vu veličinu, lamelarnost (broj dvosloja u jednoj čestici), sastav tvari, koje čestici daju posebna svojstva poput naboja, u dvosloju itd. Ta se karakteristika počela promatrati sa velikim zanimanjem kada je riječ o neurodegnerativnim bolestima poput Alzheime- rove bolesti, Parkinsonove bolesti, glioma i sl. U slučaju bolesti središnjeg živčanog sustava (CNS) najveći problem predstavlja krvno–moždana barijera koja je lokali- zirana na čvrstoj vezi između endotelnih stanica moždanih kapilara i drugih stanica (pericita, astrocitnih nastavaka, neuronskih nastavaka) koje tvore dodatni čvrsti sloj oko njih. Rezultati dosadašnjih istraživanja sa liposomima kao terapeutskim agen- sima, čija je zadaća dostavljanje terapeutika do specifičnog tkiva, i dijagnostičkim agensima, koji sadrže molekulske markere za detekciju stanja nekog tkiva, pokazali su se pozitivnom smjernicom za daljnji razvoj. Do danas se na tržištu nalazi velik broj lijekova koji koriste upravo liposome kao nanonosače, no za bolesti, čija je etimologija neurološke prirode, taj je stupanj tek potrebno dostići. Following the steps of currently rapid development of nanotechnology, medicine has turned its perspective in the same way and that is the synthesis of nanoparticles which will improve our dealing with modern health issues. Since their discovery in the second half of the 20th century, nanoparticles have shown nothing but promising outcomes in solving diseases which humankind is coping with. There is a variety of available nanoparticles like micelles, biocompatible polymers, microchips etc., but the most optimistic and worth to mention ones are liposomal nanoparticles. Liposomes are spherical particles, which vary from 50 to 450 nm in size, and are composed of one or more concentric phospholipid bilayers. Bilayers are oriented in a way that the ”heads” of outer and inner phospholipid molecules in a bilayer are in contact with aqueous medium. A formation of a bilayer like this provides liposomes to encapsulate both lipophlic and hydrophilic molecules in their membrane or aqueous core, respectively. Due to the great diversity of possible liposomal designs, methods of synthesis may vary from experiment to experiment. Liposomes can be designed differently by the criteria like size, lamellarity, types of molecules incorporated in their membranes etc. This interesting characteristic became popular in a field of developing therapeutics that are ment to ease the symptoms or even cure some of the neurodegenerative diseases like Alzheimer’s disease, Parkinson’s disease, gliomas etc. When it comes to central nervous system (CNS) illnesses, there is a problem in overcoming the blood–brain barrier (BBB) which strictly regulates the transferal of molecules between blood and CNS. BBB is localized in the endothelial cells of brain capillaries and other types of cells (pericytes, astrocyte foots, neuronal foots) which form another protective layer over those capillaries. Results of current experiments showed that liposomes have a great future in being therapeutic (which are programmed to carry a therapeutic drug)and diagnostic (which carry biomarkers for external detecting) agents. Up until now, many liposomal drugs are being used in treating diseases, but the ones which will be specialized in overcoming the BBB have yet to reach this level. |
